Free orbital surface treating tool

ABSTRACT

There is provided a tool for treatment or modification of a surface, for example, buffing, having drive means including a shaft, an eccentric member secured to the shaft and rotatable therewith, a supporting member which is adapted to support a surface modifying agent, e.g. buffing material and buffing compound, the support member being characterized by a recess dimensioned to surround a peripheral portion of the eccentric, and bearing means coacting between the recess and the eccentric to enable the eccentric to rotate freely relative to the support member.

United States Patent [72] Inventors James Glenn Satterthwaite 1 Dogwood Trail, Chesapeake, Va. 23703; Waverly Hope Wilcox, 1214 Sheppard Ave., Norfolk, Va. 23500 [21] Appl. No. 774,393

[22] Filed Nov. 8, 1968 [45] Patented May 25, 1971 [54] FREE ORBITAL SURFACE TREATING TOOL 10 Claims, 2 Drawing Figs.

[52] U.S. C1 51/120,

[51] Int. Cl B241) 23/02 [50] Field ofSearch 51/119,

[56] References Cited UNITED STATES PATENTS 2,794,303 6/1957 Wickes 51/119X 2,942,384 6/1960 Higley 51/1702 3,364,625 1/1968 Sogge 51/17OX 3,482,362 12/1969 Bangerter et a1. 51/120X 3,416,177 12/1968 Young 15/98 Primary Examiner-Lester M. Swingle AttorneyMcNenny, F arrington, Pearne & Gordon ABSTRACT: There is provided a tool for treatment or modification of a surface, for example, buffing, having drive means including a shaft, an eccentric member secured to the shaft and rotatable therewith, a supporting member which is adapted to support a surface modifying agent, e.g. buffing material and buffing compound, the support member being characterized by a recess dimensioned to surround a peripheral portion of the eccentric, and bearing means coacting between the recess and the eccentric to enable the eccentric to rotate freely relative to the support member.

I 1 FREE OItBl'I'AL suamcs TREATING TOOL BACKGROUND OF THE INVENTION PRIOR ART Various types of free orbital motor driven tools are used for grinding, sandingpolishing, and other such kinds of surface treatment operations. In such machines eccentric or orbital motion is sometimes achieved by mounting two shafts in sideby-side relation with a proper distance between centers, and wherein one shaft is laterally displaced with respect to the other in order to allow one shaft and its bearing assembly to swing or move in an eccentric fashion withoutinterference from the other shaft. In such an arrangement, difficulty is encountered when'relatively small eccentricity is desired since it is necessary to reduce the shaft and bearing sizes and thereby weaken the structure, A typical example of such a structure is shown in U.S. PatNo. 2,967,315 dated Jan. 10, 1961.

To overcome the problem of shaft sizes and relative lateral displacement of theaxis of the shafts, structures are sometimes used wherein the two shafts are longitudinally displaced as shown in U.S. Pat. No. 2,794,303 dated June 4, I957. Such structure additional length in the orbit drive and produces undesirable balancing problems and large force couples which must be absorbed by the bearings.

Although such machines may function for their intended purposes, they present problems. It is desirable that the freedom of the surface treating medium supporting member to rotate about its own this and the mechanism by which eccentricity is introduced into the motion of the surface treating medium supporting j member be accomplished in the same plane or close to the'same plane. Still further, it is desired that the shaft extending from the drive means shall not require reduction in diameter and consequent loss of strength in order to accommodate a second shaft. Still further, his desired to simplify the structure bothas to material used and as to cost'of manufacture so that the cost of manufacture may be minimized.

s'bMMAav or INVENTION plane." This allowsfor minimum overall height of the machine which is of importance in many applications and minimizes problems of bearing loading and balancing. Further, the structure of the present invention allows for greater strength since the diameter of the shaft of the drive means need not be restricted to accommodate a second shaft. The second shaft is eliminated, and the operations necessary in manufacture-of the apparatus of the ptesent'invention and minimized and simplified. For example, as will be hereinafter more particularly explained, a large bearing is provided which rotates ecccntrically and surrounds the main motor drive shaft This bearing may be pressed onto a retaining shoulder provided in the eccentric member and when so presed it holds tightly without setscrews or retaining plates.

A driven disc, or surface treating medium supporting member, is directly formed of rubber and is mounted-directly over the outer rim of the eccentric bearing by a simple clamping action. Thedtiven is provided with a hub or rim which has a sufiicient depth in a preferred embodiment to allow it to extend slightly beyond the width of the bearing. When clamped in this position, there is sufficient deformation of the resilient rubber material to effect an overlapping of the edge of the bearing. This overlap assists in mechanically locking the disc firmly on the bearing until the compressive stress is 2 released. The rubber disc may be formed with a hardness selected to provide'the best operating characteristics for the particular work intended to be performed. For example, the

7 disc maybe formed 'of relativelyhard or soft material in the range from 70 on the Shore D scale to on the'Shore A scale. The driven disc may formed of any other material, e.g. plastic, aluminum, etc., although for convenience an elastomeric material-is preferred.

A suitable housingfor the motor may be providedan'd fitted with handles for manual operation, or with an upwardly extendingrod and handle for use by an operator in a standing position. For convenience, the invention will be described with reference to an electrically driven apparatus of the hand tool type, it beingunderstood that the principlesof the invention may be embodied in many-other forms-of tools. The

devices of this invention may also'be used in multiples in a single tool; for example, a double or triple head floor polishing or grinding .tool witltsuitable'coupling means for driving plural heads. While electric motor drive means are preferred, it will also be understood that the invention may be embodied using pneumatic drive means or any other suitable driving mechanism Briefly, stated, then, this invention is in a free orbital, surface treating tool comprising in combination drivemeans including a shaft member rotatable about its longitudinal axis. To the shaft is secured by any suitable means an eccentric member rotatable with the shaft. A support for a surface treating medium, e'.g. a disc for supporting a buffing material, is provided for attachment to the eccentric. To this end, the support is provided with a recess dimensioned to surround a peripheral portion oi" the eccentric. Bearing means coact between the eccentric and therecess to allow the support to rotate freely relative to the eccentric.

and improved free orbital eccentric surface treating tool which is particularly suited for use in performingsurfacetreab' ing or modifying operations such as sanding, grinding, buffing or polishing.

Astillfurther object of this invention is to provide a novel and improved apparatus which reduces the number of parts and part complexity to provide a simple and rugged tool.

Another important object of this invention is to provide a novel and improved free orbital eccentric surface treating tool in which the counterbalancing means for the eccentric is advantageously disposed with respect to access and'with respect to minimizing forced couples on the mechanism.

Further objects and advantages of the invention will appear from the following description and the annexed drawings wherein:

FIG. I is an elevation, partially in'section and partially phantom showing a preferred embodiment of the present invention, and having a shroud or housing therefor fitted with appropriate laterally extending handles to facilitate manual operation, the shroud being shown in phantom.

FIG. 2 isa perspective viewof an eccentric and'counterbalance useful in accordance'with the present inventiomand adjacent the bearing housing 18. It is to be understood that while the electric motor shown in the annexed drawings is provided with a projecting'shaft, other structures may be employed; for example, the shaftend could be flush with the motor housing and by being provided with internal attachment means,-e.g.' threads or-slot and key means, enable attachment of a driven "member'whichitself is provided with a projecting shaft. Special treatment of the shaft portion 12 is not required and reduction in diameter to accommodate other parts is rendered unnecessary as will be explained below. Although any suitable means for attaching the housing or shroud 20 to the motor may be employed, in the embodiment shown in FIG. 1, studs 22 extending rearwardly from the motor and fitted with finishing nuts 24 may be used to cooperate with circumferentially disposed mounting bosses 26 to retain the housing or shroud on the apparatus. In the device illustrated, three such mounting bosses 26 disposed at 120 intervals have been found to be satisfactory. As indicated above, the shroud or housing 20 may be of any suitable configuration as may be determined by the operation to be performed. In fact, in some embodiments of the invention, a series of interchangeable shrouds may be provided to better accommodate the apparatus to different surface treating operations.

The characterizing components of the present invention are shown in section in FIG. 1. There is provided an eccentric body 28 which may be formed of a suitable cast metal, e.g. iron or aluminum. The eccentric body 28 is provided with a bore 30 which may in turn be provided with internal threads 32 for fastening coaction with the threaded projecting portion of the drive shaft. Other than thread means, any suitable means of securing the eccentric body 28 to the drive shaft portion 12 may be employed such as, for example, a key slot and key, or a shrink-fit of one part to the other. With the thread fastening means or the key-slot fastening means, the eccentric 28 may be replaced with a different eccentric body having a different degree of eccentricity. The feature of interchangeability renders the present apparatus adaptable to a larger variety of surface treating operations in a much simpler fashion than heretofore possible with, for example, the twoshaft devices of the prior art.

FIG. 2 shows in perspective a form of eccentric which is especially suitable for use in the present invention. As shown in FIG. 2, the eccentric member consists of a disc body 28 having a bore 30 radially displaced from the center and extending into the disc body 28 on an axis which is parallel to the major axis of the eccentric body 28. In the embodiment shown, the bore 30 is provided with threads 32 for mating coaction with the threads 14 of the drive shaft 12. In order to balance eccentric body 28 for rotation, counterbalancing means are provided in the form of a counterbalancing mass 34 which is secured to eccentric body 28 by means of laterally extending am 36. The counterbalancing mass 34 in the embodiment shown is in the form of a segment of a circle, and its mass coupled with the mass of the arm 36 is sufficient to adjust the static balance of the rotating and orbiting system so that its center of mass is located on the axis of rotation through the center of bore 30. The particular configuration of counterbalance mass 34 is desirably, although not essentially, completed in the form of rim 37 which is supported opposite the mass 34 by arm 39 to incorporate an additional safety feature in the devices hereof minimizing injury from rotating mass 34. The remote face 52 (FIG. I) of eccentric body 28 is provided with a circumferential groove 54.

As shown best in FIG. 1, counterbalancing mass 34 is axially inwardly displaced toward the body of the drive motor 10 because of the configuration of arm 36 which is integral therewith. The mass 34 is displaced so that it orbits in the spacial annulus bounded by the motor bearing housing 18, the forward face 38 of the electric motor 10, and the projection of the sidewall or cover of the motor 10. This utilizes available space efficiently for the accommodation of the counterbalancing mass 34 so that it does does not extend beyond the periphery of the housing of electric motor 10. The displacement in an axial direction toward the motor 10, although relatively small, enables easy access to the clamp 40 for ready replacement of the eccentric disc 28 or interchange of surface treating media. At the same time, the displacement is not so great as to introduce intolerable unbalancing forces due to the force couple fomred by the axial displacement.

Also shown in FIG. 1 is a support means for a surface treat ing medium. In the embodiment shown this support means is in the fonn of a rubber disc 42 having a remote surface 44 and an adjacent surface 46, the terms remote" and adjacent being in reference to the front face 38 of motor 10. Disc 42 is conveniently molded from medium hard to hard rubber and provides a support to which may be secured by any suitable means a surface treating medium of any desired nature. For example, a sandpaper disc may be adhered to the remote surface 44 of disc 42. Alternatively, disc 42 may be partially enveloped in a fabric material of the type commonly used for polishing or buffing. Altemately, disc 42 may be formed from an abrasive composition.

The adjacent surface 46 of disc 42 carries centrally located thereon a recess 48 conveniently formed by upstanding, concentrically disposed rim 50 which is dimensioned so as to surround the lower portion of the eccentric body 28 and the drive shaft 12 carried therein. As indicated above, the remote face 52 of eccentric body 28 is provided with a circumferential groove 54 which is dimensioned to receive the inner race 58 of an antifriction bearing 56 with a press fit. In the illustrated embodiment this simple press fit mounting provides the entire coupling between the bearing 56 and the eccentric body 28 but, if desired, other mounting means may be provided.

The disc 42 is removably mounted on the outer race 60 of the bearing by a clamp 40 which applies a releasably compressive stress to the rim 50. Preferably the rim is proportioned when unstressed so that it easily slips over the outer race. When disc 42 is formed from a rubber material, and clamp 40 is compressed about the outer periphery of rim 50, the resulting compressive force is sufficient to retain body 28 on bearing 56 in such a manner that relative movement in an axial direction is prevented while relative rotation between eccentric body 28 and disc 42 may occur freely. In the preferred embodiment shown in FIG. 1, the axial extension of rim 50 is desirably slightly greater than the axial width of ball bearing 56 so that when clamp 40 is actuated to impose a releaseable comprmive stress on rim 50, a circumferential inward bulge of the rubbery material is caused to be formed as a lip 64 behind the bearing race 60. This lip 64 serves to increase the axially outwardly directed thrust loads sustainable by the disc 42 and thereby improve its retention on eccentric body 28.

Of course, any suitable means for securing the surface treating supporting member, for example dim 42 on eccentric body 28, may be employed, that shown in FIG. 1 being, however, a preferred embodiment.

In operation, the apparatus shown in FIG. 1 is provided with a suitable surface treating medium which is secured to disc, 42. For example, a buffing pad of generally circular configuration of larger diameter than disc 42 and having a circumferential drawstring or an elastic margin may be secured to disc 42 in the conventional manner. For polishing or buffing, an eccentricity of the order shown in FIG. 1 is convenient. For some grinding operations, a smaller eccentricity may be desired. Accordingly, a suitable eccentric body 28 is selected and secured to shaft 12 as by threading thereon. The eccentric 28 carries a ball bearing 56 press fitted thereto in the groove 54. Disc 42 with or without an attached buffing pad (not shown) is positioned over the outer race 60 of ball bearing 56, and the clamp 40 tightened with a screw driver sufficiently to compressively stress rim 50 to an extent sufficient to retain disc 42 in place on the eccentric body 28, and desirably sufficiently to create a circumferential lip 64 behind the inner marginal edge of outer edge race 60 of ball bearing 56. If the disc 42 is not provided with a surface treating medium, it may be affixed at this time.

Suitable electrical connections are provided so that the motor can be operated by means of toggle switch 68. Laterally extending handles 70 provide a suitable structure for holding the apparatus in position against the surface being buffed. Skirt portion 72 of shroud 20 encloses the mechanism of the forward portion of the motor sufiiciently that the operator is not exposed to the rapidly rotating counterbalancing mass 34.

At the same time, access to the clamp 40 is possible so the changing of the is easily accomplished.

Although a preferred embodiment of this invention is illus trated, it is to be understood that various modifications and rearrangements of parts may be resorted to without departing from the scope of the invention.

We claim:

1. A free orbital surface treating tool comprising in combination:

a. electric motor drive means having a shaft member rotatable about its longitudinal axis;

b. a disc-shaped eccentric member secured to said shaft and rotatable therewith, said eccentric member having a bearing retaining circumferential groove on its remote face. and including an eccentrically disposed shaft receiving bore, a counterbalancing mass supported on an arm in counterbalancing relation to said eccentric member, said arm extending in a radial direction from said eccentric member and supporting said mass at its outer extremity in axially displaced relation, the direction of axial displacement being toward said drive motor;

c. a resilient elastomeric disc having a planar remote surface for supporting a surface treating medium in juxtaposed relation and an integrally concentrically located circular rim defining a recess on its adjacent surface, said rim being dimensioned to encompass the eccentric member and shaft secured therein;

d. ball bearing means having an inner race tightly secured in said circumferential groove on said eccentric member and its outer race under radially inwardly directed releasable compressive stress of said rim;

' e. clamping means compressing said rim and coacting with said rim to secure said disc to said bearing outer race.

2. A free orbital surface treating tool comprising in combination, drive means including a shaft member rotatable about its longitudinal axis, an eccentric member secured to said shaft member and rotatable therewith, an antifriction bearing having inner and outer races extending around said eccentric member with said inner race secured thereto, planar means having adjacent and remote surfaces for supporting a surface treating medium in juxtaposed relation to said remote surface and including on the adjacent surface a recess providing an inner wall surrounding said outer race and at least part of said eccentric member, releasable clamp means operable radially of said outer race and radially aligned therewith to releasably clamp the outer surface of said outer race to secure said planar means to said outer race with said inner wall around said outer race, and a balancing mass carried by said eccentric member movable along a path spaced from but substantiaily adjacent to said releasable clamp means.

3. A free orbital surface treating tool as set forth in claim 2 wherein said planar means includes a flange extending from said adjacent surface and cooperating therewith to provide said recess, and said clamp means are carried by said flange.

4. A free orbital surface treating tool as set forth in claim 3 wherein said flange is radially deformable, and said clamp means is a clamp ring surrounding said flange radially deforming said inner wall into tight engagement with said outer race.

5. A free orbital surface treating tool as set forth in claim 4 wherein said planar means is free to rotate about said central axis with said eccentric member.

6. A free orbital surface treating tool as set forth in claim 5 wherein said planar means including said flange is a unitary body of elastomeric material.

7. A free orbital surface treating tool as set forth in claim 4 wherein the axial spacing between said adjacent surface and said balancing means approaches the axial height of said clamping ring.

8. A free orbital surface treating tool as set forth in claim 4 wherein said eccentric member is circular in plan shape and includes an eccentrically disposed shaft receiving bore, said shaft extending into said bore with at least a portion thereof surrounded by said flan e.

9. A free orbital su ace treating tool as set forth in claim 4 wherein said balancing means is integrally formed with said eccentric member.

10. A free orbital surface treating tool as set forth in claim 4 wherein said planar means is a circular disc. 

1. A free orbital surface treating tool comprising in combination: a. electric motor drive means having a shaft member rotatable about its longitudinal axis; b. a disc-shaped eccentric member secured to said shaft and rotatable therewith, said eccentric member having a bearing retaining circumferential groove on its remote face, and including an eccentrically disposed shaft receiving bore, a counterbalancing mass supported on an arm in counterbalancing relation to said eccentric member, said arm extending in a radial direction from said eccentric member and supporting said mass at its outer extremity in axially displaced relation, the direction of axial displacement being toward said drive motor; c. a resilient elastomeric disc having a planar remote surface for supporting a surface treating medium in juxtaposed relation and an integrally concentrically located circular rim defining a recess on its adjacent surface, said rim being dimensioned to encompass the eccentric member and shaft secured therein; d. ball bearing means having an inner race tightly secured in said circumferential groove on said eccentric member and its outer race under radially inwardly directed releasable compressive stress of said rim; e. clamping means compressing said rim and coacting with said rim to secure said disc to said bearing outer race.
 2. A free orbital surface treating tool comprising in combination, drive means including a shaft member rotatable about its longitudinal axis, an eccentric member secured to said shaft member and rotatable therewith, an antifriction bearing having inner and outer races extending around said eccentric member with said inner race secured thereto, planar means having adjacent and remote surfacEs for supporting a surface treating medium in juxtaposed relation to said remote surface and including on the adjacent surface a recess providing an inner wall surrounding said outer race and at least part of said eccentric member, releasable clamp means operable radially of said outer race and radially aligned therewith to releasably clamp the outer surface of said outer race to secure said planar means to said outer race with said inner wall around said outer race, and a balancing mass carried by said eccentric member movable along a path spaced from but substantially adjacent to said releasable clamp means.
 3. A free orbital surface treating tool as set forth in claim 2 wherein said planar means includes a flange extending from said adjacent surface and cooperating therewith to provide said recess, and said clamp means are carried by said flange.
 4. A free orbital surface treating tool as set forth in claim 3 wherein said flange is radially deformable, and said clamp means is a clamp ring surrounding said flange radially deforming said inner wall into tight engagement with said outer race.
 5. A free orbital surface treating tool as set forth in claim 4 wherein said planar means is free to rotate about said central axis with said eccentric member.
 6. A free orbital surface treating tool as set forth in claim 5 wherein said planar means including said flange is a unitary body of elastomeric material.
 7. A free orbital surface treating tool as set forth in claim 4 wherein the axial spacing between said adjacent surface and said balancing means approaches the axial height of said clamping ring.
 8. A free orbital surface treating tool as set forth in claim 4 wherein said eccentric member is circular in plan shape and includes an eccentrically disposed shaft receiving bore, said shaft extending into said bore with at least a portion thereof surrounded by said flange.
 9. A free orbital surface treating tool as set forth in claim 4 wherein said balancing means is integrally formed with said eccentric member.
 10. A free orbital surface treating tool as set forth in claim 4 wherein said planar means is a circular disc. 